Trainer except lightning: create a separate buck target

Summary:
Pull Request resolved: https://github.com/facebookresearch/d2go/pull/555

The TARGETS for the files inside the directory `trainer` are tackled in two parts.
1. This diff creates TARGETS for the files inside `trainer` i.e. except `trainer/lightning`
2. The diff D46096373 creates TARGETS for files inside `trainer/lightning`

Reviewed By: tglik, wat3rBro

Differential Revision: D45912069

fbshipit-source-id: 3026250a49978f1b8e7a48aeebe1914d8a0a692b

d2go/trainer/fsdp.py

@@ -9,7 +9,7 @@ from typing import Callable, Generator, Iterable, Optional
 import torch
 import torch.nn as nn
 from d2go.config import CfgNode as CN
-from d2go.modeling import modeling_hook as mh
+from d2go.modeling.modeling_hook import ModelingHook
 from d2go.registry.builtin import MODELING_HOOK_REGISTRY
 from d2go.trainer.helper import parse_precision_from_string
 from detectron2.utils.registry import Registry
@@ -265,7 +265,7 @@ def build_fsdp(
 
 
 @MODELING_HOOK_REGISTRY.register()
-class FSDPModelingHook(mh.ModelingHook):
+class FSDPModelingHook(ModelingHook):
     """Modeling hook that wraps model in FSDP based on config"""
 
     def apply(self, model: nn.Module) -> FSDPWrapper: